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Another XS400 'starting on one cylinder' thread.


xmastree
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Having done the valve clearances (and fitted new plugs), I tried to fire it up...

Nothing at all, not even trying to fire. Then I noticed that whilst I had the throttle cable off, it had become dislodged at the twistgrip end and the throttle wasn't fully closing. There was a gap of about 1/4" at the idle adjuster screw.

Fixed that and it fired, but still only on the left cylinder. Then it died.

It would only start with full choke and absolutely no throttle. And only on one cylinder. Trying to open the throttle kills it instantly, and it will just about keep going after about the fourth attempt. Then, slowly, the throttle can be opened and the speed will increase. Eventually the right hand cylinder kicks in and it will warm up and settle nicely.

It doesn't rev well though, spluttering before revving if the throttle is opened quickly.

I'm suspecting the carbs...

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Having done the valve clearances (and fitted new plugs), I tried to fire it up...

Nothing at all, not even trying to fire. Then I noticed that whilst I had the throttle cable off, it had become dislodged at the twistgrip end and the throttle wasn't fully closing. There was a gap of about 1/4" at the idle adjuster screw.

Fixed that and it fired, but still only on the left cylinder. Then it died.

It would only start with full choke and absolutely no throttle. And only on one cylinder. Trying to open the throttle kills it instantly, and it will just about keep going after about the fourth attempt. Then, slowly, the throttle can be opened and the speed will increase. Eventually the right hand cylinder kicks in and it will warm up and settle nicely.

It doesn't rev well though, spluttering before revving if the throttle is opened quickly.

I'm suspecting the carbs...

yep, pilot jets blocked ( a recurring theme in xs400 threads)

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I need a decent inline fuel filter. I stripped the carbs, and the float bowls were full of muck. When I had them apart before I had them ultrasonically cleaned. I guess the crap is coming from the tank.

I already have a filter in the line, but it obviously isn't doing its job.

Any suggestions for an effective one?

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I need a decent inline fuel filter. I stripped the carbs, and the float bowls were full of muck. When I had them apart before I had them ultrasonically cleaned. I guess the crap is coming from the tank.

I already have a filter in the line, but it obviously isn't doing its job.

Any suggestions for an effective one?

I just used a small inline paper filter.

Just because they are ultrasonically cleaned, doeasn't mean all the crud is out. Some swear by using a carb additive in the petrol tank and that clears out the gunk

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I just used a small inline paper filter.

One of these?

I fitted this type which is mesh rather than paper (and it only cost me £1 from the local bike shop...)

The one cylinder thing, I think, was due to a blockage not in the pilot jet but in that hole in the bottom of the float bowl which comes up the side IYKWIM.

At the top in this picture, next to the big alloy circle thing.

3234float_chambers.jpg

(that was when I first got it, not just now)

I think that feeds the choke (via the brass tube visible above the right side one in that picture), so it would seriously affect cold starting. I got a syringe full of fuel and forced it through the hole. It was much better after that, but if I don't get a decent filter I'll have to do it all again soon... :banghead:

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Wow those carbs were gunky!!

Mine were no where near as bad and i still had a severe blockage in which you describe. Had to soak over night and use a fuse wire and jiggle till i got compressed air through the bowl. Then i sent off to JRS to have them cleaned.

Looking at my manuals, the pilot system can't be fed direct from float chamber as it has a blanking plug over the jet so would seem to come off the starter system!!

The fuel filter you have is the same as mine. I thought they had a paper element at the top part!!

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